1. Field of the Invention
The invention relates to an infeed chute for a debarking drum and, in particular, to an infeed chute designed to accommodate two log cranes for simultaneous or near simultaneous feed from both cranes.
2. Description of the Related Art
A variety of systems have heretofore been provided for delivering logs to the inlet end of a debarking drum. One conventional method of delivery is to provide an infeed chute for receiving logs from a log crane and guiding those logs end first into the debarking drum.
A concern with all infeed chute systems is that the chute guide the logs into the debarking drum in a manner so that the logs do not bind or clog at the drum inlet so that there is a smooth, relatively continuous infeed into the debarking drum and so that there is effective debarking of the logs with a minimal risk that the logs being infed will be whipped around and pieces thereof ejected from the infeed chute, which would endanger workers in the area.
A typical log crane 10 and infeed chute 12 are shown by way of example in FIG. 1. As shown, the logs which in the illustrated configuration are tree-length are stored in a storage pile 14, which may be circular, as shown. The storage pile 14 is interrupted to accommodate the infeed chute 12 and debarking drum 16 substantially along the path defined by the storage pile and also to allow log trucks 18 to bring logs to the vicinity of the storage pile 14 so that the log crane 10 can remove logs from such trucks 18 and store the same in the storage pile 14.
The log crane 10 is provided to retrieve logs from the storage pile 12, carry the load of logs to the infeed chute 14 and release that load of logs downwardly and into the debarking drum 16. Thus, infeed into the drum is limited to a sequence of loads, the size of which is determined by the capacity of the log crane 10. Furthermore, feed of logs is interrupted as the log crane 10 is used to locate, retrieve and convey logs from the storage pile 12 to the infeed chute 14. Thus, such prior art log crane/infeed chute systems were limited by the capacity of the log crane and the time required to retrieve logs from storage pile and convey the same to the infeed chute.
In order to ensure that the logs are smoothly guided into the debarking drum 16, the infeed chute 12 has a width only slightly greater than the inlet to the debarking drum 16 (FIG. 1) and, like a funnel, guides the logs into the debarking drum 16. More particularly, a top plan view of the conventional chute of FIG. 1 is shown in FIG. 2. As can be seen, a central plate 20 of about two-thirds the diameter of the debarking drum passes centrally down the length of the infeed chute 12. Two substantially triangular plates 22 are disposed on either side of the central plate 20 to define trough walls at the inlet end of the chute 12 as shown in FIG. 3. The trough walls 22 have a width equal to about one half the diameter of the drum 16 at the inlet end of the chute (FIG. 3). The trough walls are defined at an angle A of greater than about 155 and less than about 165 degrees with respect to the central plate 20.
Another pair of triangular plates 24 are defined along a substantial portion of the trough to define severely sloping side walls to more steeply guide the logs into the debarking drum 16, as shown in FIG. 4. In this view, it can be seen that angle A remains between 155 and 165 degrees whereas angle B, defined between each plate 24 and respective plate 22, is greater than about 115 and less than about 125 degrees.
As shown in FIG. 5, as the debarking drum is approached, the trough walls or plates 22 have become quite narrow and the severely sloping side walls 24 define a substantial portion of the trough thereby concentrating the logs in the center of the chute to deliver the same into the debarking drum 16. Here again, angle A is greater than about 155 and less than about 165 degrees and angle B is greater than about 115 and less than about 125 degrees.
Adjacent the debarking drum inlet, as can best be seen in FIGS. 6 and 2, two plate segments 26,28 are mounted on each side of and to the central plate 20, trough wall plates 22 and vertical side wall plates 24, to define a transition to the debarking drum inlet. Specifically, a triangular plate 26 is mounted to the cut away distal end of central plate 20 and four sided plate 28 is mounted or coupled to the triangular plate 26, trough plate 22 and side wall 24. As shown in FIG. 6, plates 26 and 28 round out the trough immediately adjacent the inlet of the debarking drum to guide the logs thereinto.
Thus, the illustrated single crane infeed chute 12 is relatively narrow and provides a generally uniformly deepening trough with containing side walls 24 and very gradually narrowing trough walls 22 to guide the logs into the debarking drum. The capacity of that infeed chute, however, is limited to the intermittent single crane load, as described above. Debarking drums, on the other hand, are not necessarily so limited to such an intermittent, relatively small load. Indeed conventional debarking drums can receive a greater load and more continuously. In addition, debarking drums can be fairly readily scaled up to have a greater diameter and/or greater length to accommodate a greater log flow.
In order to maximize the amount of wood which can be processed in a chip mill during a given period of up or operational time, it would be desirable to increase the rate at which logs are infed into a debarking drum of either conventional or increased capacity. The efficiency of the infeed chute system described above may be increased by providing two log cranes operating in tandem to thereby reduce the delay experienced when a single crane retrieves another load of logs to be infed. However, such a second crane must wait until the first load of logs has been fully or substantially received into the debarking drum to ensure that the logs will not bind at the drum inlet because the above described conventional infeed chute is designed to accommodate only a single load of logs.